Materials for an organic EL element may be divided into a light emitting layer as the main component, a carrier transport layer for transporting holes or electrons, two electrodes i.e. a cathode and an anode, and other materials.
As materials for an organic EL element, various low molecular materials and high molecular materials are employed for such a light emitting layer or a carrier transport layer. Especially with respect to low molecular materials, many materials have been proposed.
On the other hand, also with respect to high molecular materials, electroconductive n conjugated polymers such as poly(p-phenylenevinylene), polyalkylthiophene, etc. are, for example, known (e.g. Patent Document 1), and in recent years, polymers containing triarylamines have been reported (e.g. Patent Documents 2 to 6).
And, also the present inventors have developed an efficient synthetic process for a novel triarylamine polymer containing a triarylamine in its main chain and have already filed Patent Applications (e.g. JP-A-3-273087, JP-A-08-054833, JP-A-08-259935, JP-A-11-035687, JP-A-11-292829, JP-A-13-098023, JP-A-11-021349, JP-A-11-080346, JP-A-11-080347, JP-A-11-080348 and JP-A-11-080349).
However, to use as organic EL materials, such polymers have been found to be not necessarily satisfactory, since the thermal stability of terminal moieties is low, and they have a problem in useful life.
The present invention has been made in view of the above problems, and its object is to provide a novel triarylamine polymer which is excellent in solubility and film-forming property and has improved thermal stability; a simple process for its production; and an organic EL element employing it.